When Benadryl is Dangerous (Insert scary movie music here)

My first draft on antihistamines was written by a doctor (me) that included paragraphs on receptors and pharmacology. When I reread it, I was asleep by the 2nd paragraph. So here is a 2.0 version that hits the highlights of the major antihistamines hopefully without needing a sedation disclaimer.

A is for Allegra or fexofenadine, B is for Benadryl or diphenhydramine, C is for Claritin or loratadine and Z is for Zyrtec or cetirizine.

First and foremost, Benadryl can be dangerous. Everyone knows it causes sedation in most people but some of you still contend, “It doesn’t bother me!” Here is some data to the contrary. A well known study on antihistamines was written by an author named Weiler and published in 2000 in the Annals of Internal Medicine. Using a driving simulator, he compared the effects of Benadryl, Allegra, alcohol and placebo. He measured how well subjects could follow another vehicle at a set distance, how many times they got out of their lane and reaction times when responding to an obstacle put in their path. The subjects taking Benadryl had the worst performance—worse than alcohol! They also divided up the Benadryl takers inquiring which ones felt subjectively unaffected by the drug. The study found that those people still objectively had slower reaction times. So even if you think your immune to the effects of Benadryl, studies show that to be false. The Allegra side of the study showed no effect on cognition. A lot of UPS pilots reside here in Louisville, and this study is often cited to allow UPS pilots to take Allegra while in the air.

Benadryl can also be an issue for our children. Michael Blaiss, a well known allergist in Tennessee, wrote a review in Clinical Therapeutics in 2004 about antihistamine prescribing strategies in school age children. He cites the detrimental effects of older sedating antihistamines on their “physical, social, and psychological well-being and academic performance.”

The take-home message is Benadryl should not be used routinely during the day. Newer agents such as Allegra, Zyrtec and Claritin have much better side effect profiles. Even Zyrtec cannot be called “non-sedating.” It’s also associated with sedation in some people and is therefore called “less sedating.” This becomes an issue if you operate heavy machinery or fly an airplane.

Hopefully you are still awake. Stay tuned for an article on generics versus brand name medications and how generics could save you a lot of money. Be sure to “like” my facebook page at www.facebook.com/drdamin and share this page with other allergy sufferers.

Disclaimer: This blog is not intended to create a doctor-patient relationship with any reader. If you need personalized medical advice, contact your primary care physician or other physician in your community.